A common health concern today is the wearing out of one's joints due to such factors as age, over-exertion, health, injury, and weight. In many instances, joints are replaced in a medical procedure to relieve the pain and loss of function often associated with joint wearing. Total knee replacement (“TKR”) is one such procedure. TKR involves the removal of a patient's entire knee joint, followed by the implant of prosthetic knee components. Approximately 581,000 TKR procedures are performed annually in the United States.
Knee prostheses typically last between about 15 and 20 years in a patient, by which point the prostheses has typically worn to a point of needing replacement. However, this wearing of knee prostheses can cause long-term complications well before the complete wearing of the prostheses, requiring surgery and replacement of the prosthesis prematurely. One such long-term complication is osteolysis, wherein particulate debris from wear of prosthetic components causes a local immune response, resulting in tissue damage and bone resorption. Osteolysis, which occurs in up to 10% of knee replacement patients, can cause a knee prosthesis to loosen, and in some instances can cause the bone to fracture in areas immediately surrounding the implant.
Studies have shown that excessive wear of knee prostheses and generation of particulates are often the product of high contact stress and shear forces exerted by rigid metal knee prosthesis components upon polymer knee components. Reduction of these high contact stress and shear forces is shown to increase the life of knee prostheses and decrease the generation of particulate debris from the TKR. Also, to generate a cushioning within a prosthesis can reduce peak loads and further reduce contact stress and shear forces. This results in a prosthesis that behaves and feels more like a natural knee, which in turn provides for greater patient mobility and comfort. What is needed is an improved tibial component configured to better manage the loads within a TKR through cushioning and shock absorbing features integrated into the tibial component.